Governor Charlie Baker is appointing a banker and progressive activist as his new labor secretary, he announced Friday. Rosalin Acosta, most recently an executive at Enterprise Bank in Lowell, will take over from Ronald L. Walker II on July 1.

Walker will be the first Cabinet member to leave the Republican’s administration.

Acosta, a Cuban-born graduate of Wesleyan University, worked at TD Wealth Management from 2009 to 2013, leading “seasoned professionals throughout New England . . . focusing on wealth services to high net worth individuals,” according to her LinkedIn online résumé.

Before that, from 2000 to 2009, the 53-year-old Amesbury resident held several positions at what is now Santander Bank.

Baker called Acosta “a pro” and said “she’ll be terrific” in her new role.

In an interesting twist, Acosta, a registered Democrat, has been active in progressive efforts to resist President Trump’s agenda.

“We are very passionate about patriotism,” Acosta said, according to the newspaper. “Because many of the conservatives have unfortunately laid claim on that issue. They are saying that they are the patriotic individuals and progressive Democrats are not. We are taking that back because it is not theirs to have.”

Administration officials, when asked about Acosta’s involvement, say both she and her husband plan to step down from the group this weekend.

Baker, a Republican, lavished praise on Walker’s tenure, during which he is credited with modernizing the Department of Unemployment Assistance and overseeing a smooth staff reduction after a loss of federal funds.

“His work has been extraordinary and exemplary,” Baker said. “He is the consummate gentleman, the consummate team player, and he is completely unafraid of innovation and reform. And he is fabulously good at helping the people around him feel the same way.”

Baker said that as the Massachusetts unemployment rate declined, federal funding for the labor agency dropped. In Walker’s case, Baker said, that required him to figure out a way to reduce the secretariat’s headcount by almost 30 percent over an eight-month period of time.

(State data show that in January, when Baker took office, there were 1,173 full-time equivalent jobs funded by federal money in the executive office of Labor and Workforce development. Now there are 800 jobs there funded by federal dollars.)

Baker said the reason that staff reduction didn’t make big news is because Walker did such a good job maintaining the same level of service.

Walker, a 55-year-old Quincy resident who is the administration’s only African-American Cabinet secretary, was founder and president of Next Street Financial LLC, a merchant bank that provided strategic advice and access to capital for companies and entrepreneurs in urban markets.

In an interview with the Globe, Walker declined to specify why he chose to leave at this particular point, two and half years into Baker’s term. Walker said he doesn’t yet have a job lined up, but the longtime banker is aiming to return to the private sector.

He also said he is leaving the bureaucracy on a solid footing.

“I think it’s a good transition time right now. You know, it’s been three budgets,” the Democrat said, referring to crafting spending plans for the state’s fiscal years, which begin in July. A “platform has been set. Models are in place.”

He pointed to the state unemployment rate — based on myriad economic factors — which dropped from 5.1 percent in January, 2015 to 3.9 percent in April of this year.

But he also seemed to indicate that other factors might be playing a role.

“I think it’s a good time for transition for me but, most importantly, for the governor,” he said.

Joshua Miller can be reached at joshua.miller@globe.com. Follow him on Twitter @jm_bos and subscribe to his weekday e-mail update on politics at bostonglobe.com/politicalhappyhour.